The invention relates generally to cutting dies and more specifically to registration, guidance and securement components which facilitate rapid and accurate mounting of cutting dies on the drums of rotary die cutting machines, accurate and repeatable performance and ready removal.
Solid, laminated or corrugated fiberboard, cardboard sheet stock, corrugated plastics, vinyls, felts, cloth, automotive sound deadening materials and other non-metallic materials may be cut, slit or scored into regular or irregular shapes to form, for example, inserts, carton blanks, panels, separators and advertising displays. The resulting blanks are stored and shipped flat and folded and secured or utilized in their desired shapes at the point of use. Rotary die cutting machines represent the preferred means for cutting, slitting and scoring such non-metallic materials. These machines include an upper drum or cylinder to which is secured a rotary steel rule cutting die having serrated edge rules or blades which compress the stock against a lower, contra-rotating anvil which is covered with a stiffly resilient covering. Such rotary steel rule cutting dies are capable of providing complexly configured cut, scored and slit blanks at high production rates with exceptionally good dimensional accuracy.
In recent years, such rotary die cutters have been combined on the same production line with flexographic printing presses. The combination achieves equally impressive production capability including both multiple color printing and cutting, scoring and slitting in a single pass, continuous flow operation on fiberboard or cardboard stock.
One problem that has accompanied the shift to the unitary printing and cutting production line is that downtime of either machine for service, reconfiguration or adjustment amounts to downtime for both machines. The high production rates of these machines also encourages any attempt to minimize downtime and maximize production time.
In this regard, the standard rotary die cutting machine includes a cylinder or drum having a diameter which may vary from about 7 inches (17.8 cm.) to about 26 inches (66 cm.) which provides correspondingly varying cutting lengths. The die drums include a plurality of rows of equally spaced, threaded bolt holes which receive complementarily threaded fasteners which are utilized to secure large, curved wooden die boards containing the steel cutting rules.
While the basic design of such devices is both sound and functional and such devices perform admirably, set up of a machine for a production run reveals certain shortcomings. The cutting dies must be positioned upon the drum properly and held there by hand while several fasteners are piloted and threaded into the holes within the drum. If both the width and length of the cardboard product to be cut are greater than one-half the drum circumference, the cutting die must extend over greater than 180.degree. of the drum and it must therefore be configured in two sections. The die sections and the steel cutting rules contained thereon must be carefully aligned in order for a proper continuous cutting, slitting or scoring pattern to be achieved. Typically, as well, the threaded fasteners, typically machine bolts, utilized to secure the cutting die to the cylinder are simply loose and must be available to setup people when necessary, must be installed in all suitable locations to properly secure the cutting die to the drum and must be fully released and recovered without being lost into the machine before the cutting die can be removed from the drum.
From the foregoing, it is apparent that improvements in the art of rotary cutting dies and their alignment and attachment devices would be both beneficial and useful.